The present invention relates to a structural step and more particularly a mechanical sound alarm signal for the bottom step of a ladder.
Pressure sensitive signal devices are known in the ladder art, attention being directed to U.S. Pat. No. 5,193,129, issued to Dennis A. Kramer on Mar. 9, 1993, which teaches a comparatively complex fiber-optic micro bending structure associated with a ladder rung to enhance a pressure sensitive signal and to U.S. Pat. No. 5,971,102, issued to Norma Brown on Oct. 26, 1999, which patent teaches at FIGS. 10 and 11 and Column 9, lines 33-65, another comparatively complex pressure sensitive ladder step, to provide an electrical, battery powered audible alarm.
Finally, attention is directed to U.S. Pat. No. 5,500,635, issued to J. C. Matt on Mar. 19, 1996, which teaches an even more complex impact sensing element such as a shoe, apparel, ball, or fishing lure to generate an electrical signal to a battery powered light or sound emitting unit.
The present invention provides a unique and novel mechanical structure, which is completely independent of the electrically powered signaling systems of past arrangements. The unique and novel arrangement of the present invention produces by mechanical impact or frictionally an audible step warning signal, requiring only long-wearing, comparatively reliable, relatively moveable mechanical parts which do not require the frequent parts replacement of prior art arrangements.
The novel arrangement of the present invention requires a minimum of parts, which can be readily and economically assembled with a comparatively minimum number of steps and in a comparatively minimum of space so as to produce an efficient audible alarm signal. Although the present invention provides a unique arrangement for bottom step ladder structure, it is to be understood that the novel pressure sensitive warning signal can be employed in other step and platform environments.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.
More particularly, the present invention provides a pressure sensitive mechanical sound alarm arrangement for a structural step which includes at least two relatively movable mechanical parts with at least one of the parts being returnably movable relative the other between first and second positions wherein mechanical impact or frictional contact between the parts when so moved generates an impact or friction audible sound alarm upon pressure application.
In addition, the present invention provides an arrangement wherein the impact or friction contact between the relatively moveable parts includes a spring loaded keeper member mounted on one of the relatively moveable parts and an alignable apertured retainer on the other part to removably receive the keeper in a mechanical impact or friction generated sound alarm manner.
Further, the present invention provides a modified arrangement wherein mechanical impact contact between the two relatively moveable parts includes a pivotal striker arm mounted on one of the relatively moveable parts to be cooperative with the other of the parts and an aligned clicker member mounted on the other of the parts to be struck by the pivotal striker arm in a sound alarm generating manner.
It is to be understood that various changes can be made by one skilled in the art in one or more of the several parts herein described without departing from the scope or spirit of the present invention. For example, at least a portion of the mechanical impacting or friction contacting relatively moveable part surfaces could be knurled or so configured to enhance the function of the audible sound alarm.